The invention relates to an automatically controlled washing machine with at least one fresh-water line and with a washing liquid circulation system which drains a washing liquid from the bottom of a laundry treatment space and supplies the washing liquid via a circulating line again to the laundry treatment space. A sensor device is provided on the pressure side of the circulating pump and is sensitive to a dynamic pressure and transmits, as a function of the dynamic pressure, a signal for controlling a supply valve for fresh water.
A washing machine of this type is known, for example, from Published, Non-Prosecuted German Patent Application No. DE 43 32 225 A1. This conventional washing machine has a washing liquid circulation system which drains the washing liquid from the bottom of a laundry treatment space and pumps the washing liquid via a circulating line back to the treatment space such that the washing liquid is supplied above the laundry located in the treatment space. The washing machine has at least one fresh-water delivery line which can be opened or closed by a controllable valve.
A sensor device is provided in the washing liquid circulation system. The sensor device is suitable for detecting a volume flow in the conveying direction of the pump, and the control device of the washing machine is configured in such a way that, in the event of a signal from the sensor device which indicates an absence of the volume flow, the valve is actuated in such a way that fresh water is supplied. In a preferred embodiment, the sensor device is coupled to the circulating line on the delivery side of the pump, and the supply orifice between the circulating line and the laundry treatment space is configured in such a way that, during the pumping mode, there is a dynamic pressure in the completely filled circulating line. The sensor device is correspondingly sensitive to this dynamic pressure and delivers to the control device of the washing appliance corresponding signals for opening and closing the valve of the fresh-water supply. The sensor device emits a positive signal when the washing liquid circulation system is completely filled and a dynamic pressure has been formed upstream of the supply orifice. When a positive signal is received, the control device shuts off the valve of the fresh-water supply. When the dynamic pressure is insufficient, the sensor device transmits a negative signal to the control device which causes the solenoid valve to open. The fresh-water supply is switched on and the water quantity that is needed is added. One disadvantage of this conventional washing machine is that, if various elements, for example the solenoid valve, fail, there are no safety measures installed which prevent an overflow of the washing machine.
Furthermore, the prior art discloses devices which detect that a defined water quantity in the laundry treatment space is exceeded and thereupon initiate safety measures, such as, for example, the switching-on of an emptying pump or the closing of an additional safety valve. The detection of this safety level is carried out, for example, via pressure switches or via sensors which are to be found behind an orifice present at an appropriately high point in the water ducting system.
It is accordingly an object of the invention to provide a washing machine which overcomes the above-mentioned disadvantages of the heretofore-known washing machines of this general type and which has a washing liquid circulation system, which in a simple and cost-effective way provides an overflow protection and is easy to maintain.
With the foregoing and other objects in view there is provided, in accordance with the invention, an automatically controlled washing machine, including:
a fresh-water line;
a water supply valve connected to the fresh-water line;
a laundry treatment space having a bottom region;
a washing liquid circulation system including a circulating pump, a circulating line and a sensor device;
a control device operatively connected to the sensor device;
the circulating pump having a pressure side, the sensor device being provided on the pressure side;
the circulating line being connected to the circulating pump and having a supply orifice formed therein, the supply orifice being configured such that the circulating pump provides a dynamic pressure in the circulating line when the circulating line is completely filled with the washing liquid during a pumping operation;
the washing liquid circulation system draining, with the circulating pump, the washing liquid from the bottom region of the laundry treatment space and, via the circulating line and the supply orifice, supplying the washing liquid again to the laundry treatment space above the bottom region;
the sensor device being sensitive to the dynamic pressure in the circulating line, and the sensor device transmitting to the control device a signal for controlling the water supply valve as a function of the dynamic pressure; and
the sensor device further detecting a static pressure present in the laundry treatment space and in the circulating line when the circulating pump is switched off, and the sensor device transmitting to the control device a signal for executing a safety measure when the static pressure exceeds a given safety level.
In other words, an automatically controlled washing machine with at least one fresh-water line and with a washing liquid circulation system which discharges washing liquid from the bottom of a laundry treatment space and, via a supply orifice, supplies it again to the laundry treatment space from above via a circulating line by using a circulating pump, the supply orifice being configured in such a way that, during the pumping mode, a dynamic pressure occurs in the completely filled circulating line, the washing liquid circulation system having, furthermore, a sensor device which is provided on the delivery side of the circulating pump and which is sensitive to this dynamic pressure, the sensor device transmitting to a control device of the washing machine, as a function of the dynamic pressure, a signal for controlling a supply valve for fresh water, wherein a static pressure established in the laundry treatment space, and consequently also in the circulating line, when the circulating pump is switched off is likewise detected by the sensor device, and the sensor device transmits to the control device a signal for executing safety measures when the static pressure exceeds a presettable safety level.
As explained, the object of the invention is achieved in that a static pressure established in the laundry treatment space, and therefore also in the circulating line, when the circulating pump is switched off is likewise detected by the sensor device, and the sensor device of the control device transmits a signal for the implementation of safety measures when the static pressure exceeds a presettable safety level, the sensor device of the washing liquid circulation system at the same time assuming the functions of controlling the fresh-water supply and of overflow protection. This advantageously ensures a material-saving and cost-saving sensor configuration which, moreover, is particularly easy to maintain.
Advantageously, the fresh-water line has mounted in it an additional safety valve which, in the event of a corresponding sensor signal from the overflow protection according to the invention, is closed by the control device of the washing machine. This prevents the situation where, in the case of a defective solenoid valve, fresh water is supplied out of the fresh-water line into the laundry treatment space without the water flow being checked or controlled.
In a further advantageous embodiment of the invention, there is provided, as an additional safety measure, an emptying pump which can discharge washing liquid from the bottom region of the laundry treatment space. If there is too much water in the laundry treatment space, the emptying pump can be switched on via the control device of the washing machine.
In a simple embodiment, the sensor device is advantageously configured as a pressure switch. Pressure switches of this type are commercially available and are easy to install.
In an advantageous embodiment, the pressure switch has two contacts which react to differently preset pressure levels. The contact which is used for the measurement of the dynamic pressure for controlling the fresh-water supply is different from the contact used for the measurement of the static pressure of the water quantity in the water treatment space for the purpose of overflow protection.
Advantageously, and alternatively, a single contact for the measurement of the dynamic pressure and the static pressure is provided in the pressure switch. In this particularly simple embodiment, therefore, the sensor level for the activation of safety measures and that for closing the valve for the fresh-water supply has to be set only once at a fixed value.
It is particularly advantageous if the control device of the washing machine is programmed in such a way that the circulating pump is switched off at periodic time intervals for a predetermined period of time. This automatically ensures that the elements of the overflow protection check the water level in the laundry treatment space at regular intervals.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an automatically controlled washing machine with an overflow protection, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.